Numerous forms of embodiment of ignition switches are known. In an ignition switch according to German application No. 28 27 400.2-34 the central contact is designed in the form of a segment of a ball socket, wherein a contact spring or several contact springs, also equipped ball socket segments, are engaged stacked above each other, under prestressing. The contacting by these contact springs of the contact plates arranged in the switch socket is controlled by means of helically rising profiled tracks.
This arrangement affords certain substantial advantages over the state of the art in regard to savings in expensive contact materials, easier assembly and mechanical and electrical safety of contact. On the other hand, the large scale production of the contact springs with their complex design and inherent spring action and the resultant sensitivity to deformation during transport within the manufacturing plant, requires considerable investment. Furthermore, in the case of inherent spring action and also inherent spring action supported by, for example, supplemental pressure springs, a functionally detrimental decline in contact pressure must be expected upon the occurrence of a current overload and the associated overheating of the contact springs.